<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>toString()</title>
</head>
<body>
    
</body>
</html>
<script>
    function Person(name,age,gender){
        this.name = name;
        this.age = age;
        this.gender = gender;
    }
    
    // 创建一个Person的实例
    var per = new Person("孙悟空",18,"男");
    var per2 = new Person("猪八戒",20,"男");

    /*
        当我们直接在页面中直接打印一个对象时，实际上是输出的toString()方法的返回值
            如果我们希望输出对象时不输出[Object Object],可以为对象添加一个toString()方法

    */
    Person.prototype.toString = function(){
        return "我是"+this.name+",今年"+this.age+"岁,"+"性别为："+this.gender;
    };
    console.log(per.toString());
    console.log(per2.toString());

    // console.log(per.__proto__.__proto__.hasOwnProperty("toString"));
    console.log(per);
    
</script>